The present invention relates to an exterior sign such as an emblem.
In the prior art, as shown in FIG. 1, an exterior sign 81 is attached to a vehicle as an emblem that identifies a vehicle manufacturer or a vehicle model. The exterior sign 81 includes a main body 82, which shows a symbol or a mark. The main body 82 is fixed by an adhesive member 83, such as a double-sided adhesive tape, to an attachment location 84 on a vehicle body. The main body 82 includes a transparent piece 85 as a base material of the main body 82. An ornamental plating layer 86 is applied to an inner surface of the transparent piece 85. The ornamental plating layer 86 is visible through the transparent piece 85 and shows a plated design.
When the ornamental plating layer 86 is continuously exposed to a fluid such as rainwater or a washing agent used during a carwash. This may erode or discolor the ornamental plating layer 86. To prevent such a problem, as shown in FIG. 2, a protective layer 87 may be applied to the ornamental plating layer 86. This protects the ornamental plating layer 86 from corrosion (refer to, for example, Japanese Laid-Open Patent Publication No. 2005-20769, paragraph 16).
The protective layer 87 may be formed, for example, from a one-component curing material, which is a resin material manufactured by simply mixing a base compound and a solvent. However, the desired level of corrosion resistance cannot be obtained with just the one-component curing material. Thus, when using the one-component curing material, the protective layer 87 is required to be thick. However, when the one-component curing material of the protective layer 87 is thick, components in the protective layer undergo intense contraction during curing, and the solvent of the one-component curing material may erode the ornamental plating layer 86. This disturbs the arrangement of metal atoms in the ornamental plating layer 86, lowers the brightness of the ornamental plating layer 86, and adversely affects the outer appearance.
A two-component curing material, which has a higher level of corrosion resistance than a one-component curing material, may be used for the protective layer 87. A two-component curing material is a resin material manufactured by heating a mixture of a base compound and a curing agent. However, in a two-component curing material, curing occurs when the base compound reacts with the curing agent. Thus, contraction during curing becomes more intense than a one-component curing material. This further disturbs the arrangement of metal atoms in the ornamental plating layer 86. Thus, the ornamental plating layer 86 still cannot obtain sufficient brightness.